Evil is a corruptive and destructive force only, fundamentally incapable of creation or goodness.
Formerly Evil Can't Create. Grabbing this from bradpara as per Up for Grabs status. The nature of evil is difficult to define. It is, after all, a highy subjective concept, which we never encounter in any truly concrete form. And so, writers have different ideas as to what evil means, what are its goals, its methods, its limitations. One weakness typicall ascribed to the forces of evil is that they cannot create. The Power of Creation is seen as positive and Good, the purview of a God who is probably the Big Good of any given mythos. So, Evil Is Sterile. It cannot create, cannot imagine or have new ideas, certainly cannot produce new forms of life, because Creating Life Is Awesome. It may be able to propogate, but only in the manner of The Virus, by turning everything into more of itself, without the possibility of evolution, or the retention of the unique qualities that once inhabited what existed before. Beings who have fallen under evil control, whether they are Reforged into a Minion or taken over by their Superpowered Evil Side, become cruder and twisted versions of themselves. They may gain power, but they lose crucial aspects that once made them special, and will probably not behave very intelligently. Ultimately, the hope of this kind of evil is to, at best, corrupt the whole world into being just like itself, and at worst, destroy everything. The possibility of making something new and different is anathema to it. A typical bonus is that Evil Cannot Comprehend Good. See also Evil Knockoff, The Corruption and Creative Sterility. Contrast Good Is Impotent.